Best Practices for Isolation Room Safety

May 28, 2015

Look no further than the recent Ebola case in the US to understand that one of the greatest fears in the general population is the rapid spread of infectious disease. When infectious diseases such as Ebola and MERS make an appearance, they immediately become front page news and are featured by every media outlet across America. 

While there are many strategies employed to prevent these infectious diseases from becoming an ‘outbreak’, the only way to treat patients without risking the spread of disease is through the use of isolation rooms. Isolation rooms are designed to prevent contaminated particles from spreading beyond a quarantined area by ensuring that air is exhausted from the room and filtered through a high-efficiency particulate air (HEPA) filter before it is vented outside of the building.Building_Automation-Critical_Environments-Other

The most important component in providing safety to those working in and around an isolation room environment is to control the differential pressure between the isolation room and the external space. To prevent the contaminated air from escaping the room, isolation rooms require negative air pressure relative to the outside area to ensure clean air is drawn into the room and contaminated particles inside the room are not able to escape when a door is opened.

In order to ensure that an isolation room is negatively pressurized, there are a number of tests or systems available to confirm a safe environment. We will look at each of these strategies and explain the strengths and weaknesses.

The Tissue/Smoke Test

  • How: In isolation/protection rooms without installed differential pressure sensors, hospital personnel will hold a small piece of tissue under the crack in the door. If the tissue is blowing towards the corridor, the room is positively pressure; however if it is blowing into the room then it is negatively pressured. The same test can also be performed with smoke.
  • Strength: None
  • Weakness: Least reliable of all of the safety measures. Because there are no alarms or real-time monitoring, hospitals have been known to over/under pressurize these rooms and waste more energy than typical isolation/protection rooms.


  • How: Product is installed across the corridor from the isolation/protection room; it is visible from both rooms and employs a ping-pong ball in a plastic tube which will move to whichever room is positively pressured.
  • Strength: Great visual indicator for hospital personnel; can look down corridor and quickly confirm the pressure status of each room.
  • Weakness: Very difficult to install properly; if not 100% level, product will not function properly. Similar to tissue/smoke test, because indicator is strictly visual and without data, it is less energy efficient.

Differential Pressure Sensors

  • How: Product is installed in between the corridor and isolation/protection room with pressure ports in both rooms. It will measure pressure in either Inches of Water or Pascals.
  • Strength: Much more accurate and reliable than either the tissue/smoke test or the Ball-in-Tube. Typically low maintenance, and provide real-time monitoring to the BMS.
  • Weakness: No local visual or audible indication if a room is in an alarm state.

Room Pressure Monitors

  • How: Product is installed in between the corridor and isolation/protection room with pressure ports in both rooms. It will measure pressure in either Inches of Water or Pascals.
  • Strength: Safest and most reliable solution for isolation/protection rooms. Typically employ an internal pressure sensor, which makes it much more accurate and reliable than either the tissue/smoke test or the ball-in-tube, yet it provides local audible and visual alarm state. Some products also have the ability to monitor temperature and humidity on one device.
  • Weakness: More expensive than the other solutions

Bottom Line:

The Center for Disease Control (CDC), the Facility Guidelines Institute (FGI) and the Joint Commission (JC) spent a great deal of time ensuring that healthcare and lab facilities conform to isolation room requirements, however, there are varying levels of safety associated with the different isolation room strategies. Hospitals are often fiscally constrained from making facility upgrades, but as evidenced by recent events surrounding Ebola and MERS, there has never been a greater need to ensure that the healthcare system is able to react to a potential epidemic. The smartest way to implement an isolation room strategy is to provide real time monitoring and alarm capabilities using room pressure monitors. Unlike tissue/smoke tests or the ball-in-tube, a room pressure monitor requires zero manual testing and provides both audible and visual alarming when a room has been compromised; reducing the labor required to ensure negative pressure and the possibility of a catastrophic mistake. The investment required is greater, but the peace of mind to know your facility is prepared for the worst will make the decision worth every penny.

CLICK HERE to learn more about Setra's Room Pressure Monitors.


Topics: Critical Environments, Building Automation, HVAC/R